heka foo decoder

foo_decoder.lua

local cjson = require("cjson")

function process_message()
    local payload_str = read_message("Payload")

    local ok, payload = pcall(cjson.decode, payload_str)

    if not ok then
      return -1
    end

    payload["bar"] = read_message("Logger")

    local ok, payload_with_bar = pcall(cjson.encode, payload)

    if not ok then
      return -1
    end

    write_message("Payload", payload_with_bar)
    return 0
end